What is the reason that closely linked genes are typically inherited together?
A. They are located close together on the same chromosome
B. Alleles are paired together during meiosis
C. The number of genes in a cell is greater than the number of chromosomes
D. Genes align that way during metaphase I of meiosis
The correct answer and explanation is :
The correct answer is:
A. They are located close together on the same chromosome.
Explanation:
Genes that are closely linked are typically inherited together because they are physically located near each other on the same chromosome. This proximity reduces the chances that a recombination event (which occurs during meiosis) will occur between them. Recombination, or crossing-over, is the process in which homologous chromosomes exchange genetic material. This exchange can shuffle the alleles of genes located on different chromosomes or far apart on the same chromosome. However, if two genes are very close together, the probability of a crossover occurring between them is low. As a result, these genes tend to be inherited as a block, meaning they usually stay together across generations.
To further clarify:
- Meiosis is the process by which gametes (egg and sperm cells) are formed, and it includes two rounds of division: Meiosis I and Meiosis II.
- In Meiosis I, during metaphase I, chromosomes line up at the center of the cell in pairs (homologous chromosomes). This is a crucial step in the genetic variation process, but it doesn’t directly explain why closely linked genes are inherited together.
- Genetic linkage is a phenomenon where genes that are physically located near each other on the same chromosome are more likely to be inherited together. This is because the likelihood of a crossover event between them is minimal.
If genes were located on different chromosomes (or far apart on the same chromosome), they would assort independently, as explained by Mendel’s Law of Independent Assortment. However, genes on the same chromosome tend to show linkage and are passed together more frequently than independent genes. The closer the genes are to each other on the chromosome, the more tightly linked they are.
